1. Field of the Invention
The invention relates to projection equipment and more particularly to a projector leveling and focusing aid for leveling and focusing a still image projector as well as a method for leveling and focusing more than one still image projector when images from several projectors are to be superimposed or aligned.
2. Prior Art
Most still image or slide transparency projectors are provided with leveling pads or feet on their chassis which permit a projectionist to level the projector with respect to the horizontal by manipulating the pads so that they compensate for any sloping of the surface supporting the projector.
Most of the still image projectors available to the general public for home or entertainment use require that one of the slides to be shown be first projected onto the screen. The projectionist then focuses the projector and attempts to level the projector and the image by eye i.e., the projector is manipulated until the projected image appears to him not to be sloping on the screen.
Since the leveling and focusing problems occur most frequently where the projector is repeatedly dismantled or stored and set up periodically for visual programs, there is an enormous waste of time in properly leveling and focusing these projectors.
Moreover, it is currently becoming more and more popular to present still image projections consisting of images from more than one projector wherein the images are superimposed in which case the leveling problem associated with one projector is compounded by the number of projectors being used and further, the problem of getting the various images in proper registry is created.
There are provided in the prior art structures for slides to test the performance of lenses, i.e., grid patterns which may be distorted if the lens is not properly ground, as disclosed in the British Pat. No. 742,235. The structure disclosed in this British patent, however, does not aid in the leveling of one or a series of projectors nor can it be used to ensure the proper registry of images projected from two or more projectors.
It is toward the elimination of these and other problems that the present invention is directed.